High-velocity resistance training improves executive function in mobility-limited older adults

OBJECTIVES

To examine the effect of high-velocity resistance training (HVRT) on the executive function of middle-aged and older adults with and without mobility limitations.

METHODS

Participants (n = 41, female: 48.9%) completed a supervised 12-week HVRT intervention (2 sessions/week; at 40-60% of one-repetition maximum). The sample included 17 middle-aged adults (40-55 years); 16 older adults (>60 years) and 8 mobility-limited older adults (LIM). Executive function was assessed before and after the intervention period and was reported as z-scores. Maximal dynamic strength, peak power, quadriceps muscle thickness, maximal isometric voluntary contraction (MVIC), and functional performance were also measured pre and post intervention. Training-related adaptations in cognitive measures were calculated using a Generalized Estimating Equation model.

RESULTS

HVRT improved executive function in LIM (adjusted marginal mean differences [AMMD]: 0.21; 95%CI: 0.04, 0.38; p = 0.040) although no effect on middle-aged (AMMD: 0.04; 95%CI: -0.09; 0.17; p = 0.533) and older (AMMD: -0.11; 95%CI: -0.25; 0.02; p = 0.107) participants was observed. Improvements in maximal dynamic strength, peak power, MVIC, quadriceps muscle thickness, and functional performance were all associated with changes in executive function, and changes in the first four also seem to mediate the association between changes in functional performance and executive function.

CONCLUSIONS

HVRT-induced improvement in executive function of mobility-limited older adults were mediated by changes in lower-body muscle strength, power, and muscle thickness. Our findings reinforce the relevance of muscle-strengthening exercises to preserve cognition and mobility in older adults.

Continuous Positive Airway Pressure for the Treatment of Supine Hypertension and Orthostatic Hypotension in Autonomic Failure

BACKGROUND

Supine hypertension affects most patients with orthostatic hypotension (OH) due to autonomic failure, but it is often untreated for fear of worsening OH. We hypothesized that increasing intrathoracic pressure with continuous positive airway pressure (CPAP) had a Valsalva-like blood-pressure-lowering effect that could be used to treat nocturnal supine hypertension in these patients, while reducing nocturnal pressure diuresis and improving daytime OH.

METHODS

In Protocol 1, we determined the acute hemodynamic effects of increasing levels of CPAP (0, 4, 8, 12, and 16 cm H2O, 3 minutes each) in 26 patients with autonomic failure and supine hypertension studied while awake and supine. In Protocol 2 (n=11), we compared the effects of overnight therapy with CPAP (8-12 cm H2O for 8 hours) versus placebo on nocturnal supine hypertension, nocturnal diuresis and daytime OH in a 2-night crossover study.

RESULTS

In Protocol 1, acute CPAP (4-16 cm H2O) decreased systolic blood pressure in a dose-dependent manner (maximal drop 22±4 mmHg with CPAP 16) due to reductions in stroke volume (-16+3%) and cardiac output (-14±3%). Systemic vascular resistance and heart rate remained unchanged. In Protocol 2, overnight CPAP lowered nighttime systolic blood pressure (maximal change -23±5 versus placebo -1±7 mmHg; P=0.023) and was associated with lower nighttime diuresis (609±84 versus placebo 1004±160 mL; P=0.004) and improved morning orthostatic tolerance (AUC upright SBP 642±121 versus placebo 410±109 mmHg*min; P=0.014).

CONCLUSIONS

CPAP is a novel nonpharmacologic approach to treat the supine hypertension of autonomic failure while improving nocturia and daytime OH.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT03312556.

Identification of micrognathia by prenatal ultrasound may improve timely diagnosis and management of infants with Robin sequence

OBJECTIVE

Robin sequence (RS) is a craniofacial anomaly characterized by small jaw (micrognathia) with associated tongue base airway obstruction. With advances in fetal imaging, micrognathia may be detected prenatally. This study aims to determine if prenatal recognition of micrognathia offers any advantage over being unaware of the condition until after delivery and to assess if prenatal consultation for micrognathia adds benefits beyond merely noting the presence of the condition.

METHOD

Retrospective chart review examining cases from 01/01/2010 to 12/31/2020 at an urban tertiary medical center.

RESULTS

Forty seven infants with RS were included. 40.4% (n = 19) had micrognathia/retrognathia noted on prenatal ultrasound. 47.4% (n = 9) of those 19 pregnancies saw a maternal fetal medicine (MFM) program with craniofacial consultation. Compared to 28 infants not diagnosed with micrognathia until after birth, the 19 infants identified prenatally required fewer transfers from birth hospital (p = 0.02). Additionally, those referred to MFM with craniofacial consultation had shorter lengths of stay when airway intervention was required (p = 0.05).

CONCLUSION

Prenatal recognition of micrognathia may lead to early detection and management of RS. When RS is suspected, prenatal consultation with MFM and craniofacial team may further optimize care of the infant following delivery.

Study protocol for the BRAIN Training Trial: a randomised controlled trial of Balance, Resistance, And INterval training on cognitive function in older adults with mild cognitive impairment

INTRODUCTION

Epidemiological evidence suggests that both poor cardiovascular fitness and low muscle mass or strength markedly increase the rate of cognitive decline and incident dementia in older adults. Results from exercise trials for the improvement of cognition in older adults with mild cognitive impairment (MCI) have reported mixed results. This is possibly due to insufficient exercise intensities. The aim of the Balance, Resistance, And INterval (BRAIN) Training Trial is to determine the effects of two forms of exercise, high-intensity aerobic interval training (HIIT) and high-intensity power training (POWER) each compared with a sham exercise control group on cognition in older adults with MCI.

METHODS AND ANALYSIS

One hundred and sixty community-dwelling older (≥ 60 years) people with MCI have been randomised into the trial. Interventions are delivered supervised 2-3 days per week for 12 months. The primary outcome measured at baseline, 6 and 12 months is performance on a cognitive composite score measuring the executive domain calculated from a combination of computerised (NeuroTrax) and paper-and-pencil tests. Analyses will be performed via repeated measures linear mixed models and generalised linear mixed models of baseline, 6-month and 12-month time points, adjusted for baseline values and covariates selected a priori. Mixed models will be constructed to determine the interaction of GROUP × TIME.

ETHICS AND DISSEMINATION

Ethical approval was obtained from the University of Sydney (HREC Ref.2017/368), University of Queensland (HREC Ref. 2017/HE000853), University of British Columbia (H16-03309), and Vancouver Coastal Health Research Institute (V16-03309) Human Research Ethics. Dissemination will be via publications, conference presentations, newsletter articles, social media, talks to clinicians and consumers and meetings with health departments/managers.It is expected that communication of results will allow for the development of more effective evidence-based exercise prescription guidelines in this population while investigating the benefits of HIIT and POWER on subclinical markers of disease.

TRIAL REGISTRATION NUMBER

ACTRN12617001440314 Australian New Zealand Clinical Trials Registry.

Abstract 059: Continuous Positive Airway Pressure In The Treatment Of Nocturnal Supine Hypertension And Orthostatic Hypotension In Autonomic Failure

Supine hypertension affects most patients with autonomic failure (AF), complicates the treatment of orthostatic hypotension (OH) and induces nocturnal pressure diuresis, resulting in nocturnal volume depletion and worsening of daytime OH. However, it is often untreated for fear of worsening OH. We previously showed that continuous positive airway pressure (CPAP 4, 8, 12 and 16 cm H 2 O, each for 3 min) had an acute, dose-dependent, blood-pressure (BP)-lowering effect in these patients (maximal systolic BP [SBP] drop 22±4 mmHg with CPAP 16) driven by reductions in stroke volume (-16+3%) and cardiac output (-14±3%), suggesting a Valsalva-like effect. In this study, we hypothesized that overnight CPAP therapy can improve nocturnal supine hypertension, nocturia and daytime OH. Eleven AF patients with supine hypertension (age 74±2 years, 8 men, supine SBP 179±7 mmHg) had placebo or CPAP (8-12 cm H 2 O) applied for 8 hours (10pm-6am) in 2 separate nights. Supine BP was measured every 2 hr from 8pm-8am. Morning orthostatic tolerance was assessed at 8am. SBP significantly decreased during overnight CPAP therapy compared to placebo (Figure; P=0.044 by mixed-effects model) with a maximal reduction of 25±5 mmHg at 4 hours of CPAP. This BP effect was associated with lower nighttime diuresis (609±84 versus placebo 1004±160 mL; P=0.004) and improved morning orthostatic tolerance (AUC upright SBP 642±121 versus placebo 410±109 mmHg*min; P=0.014). In conclusion, CPAP is potentially a novel non-pharmacologic approach to treat the supine hypertension of AF that can improve nocturia and daytime OH.

Depression and anxiety symptoms remained elevated after 10 months of the COVID-19 pandemic in southern Brazil: findings from the PAMPA cohort

Objectives

This study aimed to examine the changes in depression and anxiety symptoms among Brazilian adults over 10 months of the COVID-19 pandemic.

Study design/Methods

The present study used data from wave 1 (June/July 2020) and wave 2 (December 2020/January 2021) of the Prospective Study About Mental and Physical Health (PAMPA) Cohort, a state-level, ambispective longitudinal study with adults from southern Brazil. The frequency of anxiety and depressive symptoms was assessed using the Hospital Anxiety and Depression Scale. Anxiety and depressive symptoms before social distancing were retrospectively assessed during wave 1.

Results

Most of the 674 participants were classified as non-symptomatic for depressive (85.0%) and anxiety symptoms (73.2%) before the COVID-19 pandemic. At wave 1, there were increases in symptoms of depression (7.6% [95% confidence interval [CI]: 7.2%, 8.1%]) and anxiety (9.1% [95% CI: 8.6%, 9.5%]). These decreased at wave 2 (depression: 6.9% [95% CI: 6.5%, 7.2%]; anxiety: 7.4% [95% CI: 7.1%, 7.8%]) although they were still elevated compared with pre-COVID (depression: 4.5% [95% CI: 4.2%, 4.8%]; anxiety: 5.8% [95% CI: 5.5%, 6.1%]). Adults living alone (b = 0.44 [95% CI: 0.07, 0.82]) had a faster trajectory in anxiety symptoms than their counterparts. Cohort members who were living alone (b = 0.24 [95% CI: 0.06, 0.42]) and with diagnosed chronic disease (0.32 [95% CI: 0.18, 0.46]) had a faster increase in depressive symptoms than their respective counterparts. Participants aged ≥60 years showed a slower trajectory of depressive (b = −0.46 [95% CI: −0.73, −0.18]) and anxiety (b = −0.61 [95% CI: −1.20, −0.02) symptoms.

Conclusions

During 10 months of COVID-19, anxiety and depression symptoms improved but were still higher than before COVID-19.

The Safety and Efficacy of Mandibular Distraction Osteogenesis Among Infants Less Than 3 kg

OBJECTIVES/HYPOTHESIS

Mandibular distraction osteogenesis (MDO) is a safe and effective surgery to address respiratory and feeding issues due to micrognathia in patients with Robin Sequence (RS). Previous studies examining postoperative complications in neonates receiving MDO have considered 4 kg as the cut-off for low weight; however, an increasing number of MDO interventions are performed in infants <4 kg. To determine if a weight <3 kg at time of MDO is a risk factor for postoperative complications or need for subsequent tracheostomy or gastrostomy tube (G-tube).

STUDY DESIGN

Retrospective chart review.

METHODS

A retrospective review of all infants <6 months of age undergoing MDO at two tertiary pediatric hospitals from 2008 to 2018. Demographic data, syndromic status, weight, and age at time of surgery, length of postoperative hospital stay, and postoperative outcomes were recorded including tracheostomy placement, G-tube placement, hardware infection, reintubation, facial/marginal mandibular nerve damage, and need for revision MDO.

RESULTS

Sixty-nine patients with RS were included. The mean age at MDO was 25 ± 20 days and mean weight was 3.32 ± 0.44 kg. There was no statistically significant correlation between weight (P = .699) or age (P = .422) and unfavorable postoperative outcomes. No patients (0%) underwent tracheostomy pre-MDO. Two patients (2.9%) required tracheostomy postsurgery; neither was <3 kg. Eight patients (11.6%) required a G-tube postoperatively.

CONCLUSION

Newborns <3 kg who undergo MDO experience the same rates of success and complication as larger infants, suggesting that MDO is a safe and efficacious procedure in infants less than 3 kg. Laryngoscope, 2021.

Physical activity attenuates the risk for dementia associated with aging in older adults with mild cognitive impairment. Findings from a population-based cohort study

From 2016 to 2040 the number of people with dementia in the United Kingdom is expected to increase by 57%, while 70% percent of it is due to a higher life expectancy. Thus, we analyzed the overall and age-stratified effect of physical activity on risk of dementia in participants with mild cognitive impairment (MCI) of the English Longitudinal Study of Ageing (ELSA). Participants of the ELSA, aged over 50 with MCI, were followed-up nine times between 2002 and 2019. Physical activity was assessed using a self-reported, validated questionnaire and participants were classified as inactive, low, or moderate-to-high active. Medical diagnosis of dementia was self-reported or determined using the Informant Questionnaire on Cognitive Decline in the Elderly. Data from 521 participants with MCI were analyzed (56% women; mean [SD] age, 68.7 [10.6]). Over 17-year follow-up, 20.5 (95%CI: 17.3 to 24.2)% were diagnosed with dementia. The risk of incident dementia was reduced in participants engaging in low (HR: 0.34; 95%CI: 0.22 to 0.54) or moderate-to-high (HR: 0.16; 95%CI: 0.08 to 0.33) levels of physical activity. Risk of dementia in adults aged 80 or more engaging in low or moderate-to-high levels of physical activity was not different from inactive adults aged between 50 and 69 years. Results were sustained after competing risk regression model and sensitivity analyses to reduce the impact of reverse causality. Physical activity appears to minimize the risk associated with aging in older adults with MCI.

Abstract P193: Effect Of Nitroglycerin And Sympathetic Withdrawal On Splanchnic Capacitance And Cardiac Blood Volumes

The splanchnic vasculature is the largest blood volume reservoir in the human body. Reduced capacitance of this vascular bed, in part due to sympathetic venoconstriction, is proposed to play a role in hypertension and heart failure. Thus, interventions that increase splanchnic capacitance or decrease sympathetic activity may be beneficial in these conditions. In a proof-of-concept study in healthy and hypertensive subjects, we evaluated whether venodilation with nitroglycerin (NTG; Study 1) or sympathetic withdrawal with trimethaphan (Study 2) increase splanchnic capacitance and reduce cardiac and stroke volumes. In Study 1 (n=10, 36±4 yrs, BMI 26.1±1.7, 4 men), abdominal and chest scintigrams, to measure regional blood volumes, were obtained before and after 0.6 mg sublingual NTG. Splanchnic capacitance (volume-pressure relationships, VPR) and compliance (VPR slope) were estimated by recording abdominal scintigrams during progressive escalation of intrathoracic pressure using continuous positive airway pressure (CPAP) at 0, 4, 8, 12, and 16 cm H 2 O, each for ≤2 min. We found that NTG increased splanchnic blood volume at rest (4%, IQR 1.81-9.95; P<0.01) resulting in a rightward parallel shift in splanchnic VPR (P slope =0.46 and P intercept =0.01), indicating an increase in splanchnic capacitance. This was associated with a decrease in cardiac blood volume (-9%, IQR 2.2-10.3; P<0.01). In Study 2, we measured blood pressure (BP) and stroke volume, used as a surrogate of venous return, during the same CPAP protocol before and during autonomic blockade with trimethaphan in 12 hypertensive subjects (49±2 yrs, BMI 29.9±1.7, 5 men). Sympathetic withdrawal decreased systolic BP (-27±14 mmHg) and produced a leftward parallel shift in VPR (i.e. reduced stroke volume; P slope =0.12 and P intercept <0.01), indicating a reduction in venous return likely due to an increase in splanchnic capacitance. In conclusion, venodilation with NTG increased splanchnic capacitance and decreased cardiac volume. Sympathetic withdrawal had similar hemodynamic effects. These findings highlight the importance of splanchnic capacitance in cardiovascular regulation.

Two-minute exercise testing is sufficient to estimate maximal cardiorespiratory fitness in people with epilepsy

We aimed to examine the agreement between submaximal cardiopulmonary exercise testing (CPET) measures and peak oxygen consumption (VO_2peak) in adults with epilepsy. Data from a randomized controlled trial with adults with epilepsy (N = 21) were analyzed. VO_2peak was assessed using indirect calorimetry during a treadmill graded maximal CPET. Oxygen uptake efficiency slope (OUES) was calculated from the relationship between oxygen uptake and minute ventilation during the entire test (OUES_peak) and the first 2 (OUES_2min), 3 (OUES_3min), and 4 (OUES_4min) minutes of the CPET. The strength of the association between measures was tested by Pearson correlation. Linear regression models were used to predict VO_2peak based on OUES from the different testing durations. Agreement between measured and predicted maximal values was tested using intraclass correlation coefficient (ICC) and Bland-Altman plots. OUES_2min, OUES_3min, and OUES_4min were highly associated with absolute (r = 0.84, r = 0.76, r = 0.75, respectively) and relative (r = 0.84, r = 0.78, r = 0.78, respectively) VO_2peak. Agreement (ICC = 0.83) between CPET-measured and OUES-predicted VO_2peak values was stronger with OUES_2min than the other time-based OUES markers. Bland-Altman plot showed satisfactory agreement between predicted and measured CPET measures with the narrowest limits of agreement observed with the OUES_2min. No potential bias was identified between these two measurements (p = 0.33). Changes in absolute (r = 0.77) and relative (r = 0.88) VO₂peak were highly associated with the change in OUES_2min. OUES_2min can be used as a surrogate for maximal cardiorespiratory fitness in adults with epilepsy. Studies with larger samples size are encouraged to confirm our findings in a more heterogeneous population.

Effects of cardiorespiratory fitness and exercise training on cerebrovascular blood flow and reactivity: a systematic review with meta-analyses

We address two aims: Aim 1 (Fitness Review) compares the effect of higher cardiorespiratory fitness (CRF) (e.g., endurance athletes) with lower CRF (e.g., sedentary adults) on cerebrovascular outcomes, including middle cerebral artery velocity (MCAv), cerebrovascular reactivity and resistance, and global cerebral blood flow, as assessed by transcranial Doppler (TCD) or magnetic resonance imaging (MRI). Aim 2 (Exercise Training Review) determines the effect of exercise training on cerebrovascular outcomes. Systematic review of studies with meta-analyses where appropriate. Certainty of evidence was assessed by the Grading of Recommendations Assessment, Development, and Evaluation (GRADE). Twenty studies (18 using TCD) met the eligibility criteria for Aim 1, and 14 studies (8 by TCD) were included for Aim 2. There was a significant effect of higher CRF compared with lower CRF on cerebrovascular resistance (effect size = -0.54, 95% confidence interval = -0.91 to -0.16) and cerebrovascular reactivity (0.98, 0.41-1.55). Studies including males only demonstrated a greater effect of higher CRF on cerebrovascular resistance than mixed or female studies (male only: -0.69, -1.06 to -0.32; mixed and female studies: 0.10, -0.28 to 0.49). Exercise training did not increase MCAv (0.05, -0.21 to 0.31) but showed a small nonsignificant improvement in cerebrovascular reactivity (0.60, -0.08 to 1.28; P = 0.09). Exercise training showed heterogeneous effects on regional but little effect on global cerebral blood flow as measured by MRI. High CRF positively effects cerebrovascular function, including decreased cerebrovascular resistance and increased cerebrovascular reactivity; however, global cerebral blood flow and MCAv are primarily unchanged following an exercise intervention in healthy and clinical populations.NEW & NOTEWORTHY Higher cardiorespiratory fitness is associated with lower cerebrovascular resistance and elevated cerebrovascular reactivity at rest. Only adults with a true-high fitness based on normative data exhibited elevated middle cerebral artery velocity. The positive effect of higher compared with lower cardiorespiratory fitness on resting cerebrovascular resistance was more evident in male-only studies when compared with mixed or female-only studies. A period of exercise training resulted in negligible changes in middle cerebral artery velocity and global cerebral blood flow, with potential for improvements in cerebrovascular reactivity.

The effect of heat therapy on blood pressure and peripheral vascular function: A systematic review and meta-analysis

NEW FINDINGS

What is the topic of this review? We have conducted a systematic review and meta-analysis on the current evidence for the effect of heat therapy on blood pressure and vascular function. What advances does it highlight? We found that heat therapy reduced mean arterial, systolic and diastolic blood pressure. We also observed that heat therapy improved vascular function, as assessed via brachial artery flow-mediated dilatation. Our results suggest that heat therapy is a promising therapeutic tool that should be optimized further, via mode and dose, for the prevention and treatment of cardiovascular disease risk factors.

ABSTRACT

Lifelong sauna exposure is associated with reduced cardiovascular disease risk. Recent studies have investigated the effect of heat therapy on markers of cardiovascular health. We aimed to conduct a systematic review with meta-analysis to determine the effects of heat therapy on blood pressure and indices of vascular function in healthy and clinical populations. Four databases were searched up to September 2020 for studies investigating heat therapy on outcomes including blood pressure and vascular function. Grading of Recommendations, Assessment, Development and Evaluations (GRADE) was used to assess the certainty of evidence. A total of 4522 titles were screened, and 15 studies were included. Healthy and clinical populations were included. Heat exposure was for 30-90 min, over 10-36 sessions. Compared with control conditions, heat therapy reduced mean arterial pressure [n = 4 studies; mean difference (MD): -5.86 mmHg, 95% confidence interval (CI): -8.63, -3.10; P < 0.0001], systolic blood pressure (n = 10; MD: -3.94 mmHg, 95% CI: -7.22, -0.67; P = 0.02) and diastolic blood pressure (n = 9; MD: -3.88 mmHg, 95% CI: -6.13, -1.63; P = 0.0007) and improved flow-mediated dilatation (n = 5; MD: 1.95%, 95% CI: 0.14, 3.76; P = 0.03). Resting heart rate was unchanged (n = 10; MD: -1.25 beats/min; 95% CI: -3.20, 0.70; P = 0.21). Early evidence also suggests benefits for arterial stiffness and cutaneous microvascular function. The certainty of evidence was moderate for the effect of heat therapy on systolic and diastolic blood pressure and heart rate and low for the effect of heat therapy on mean arterial pressure and flow-mediated dilatation. Heat therapy is an effective therapeutic tool to reduce blood pressure and improve macrovascular function. Future research should aim to optimize heat therapy, including the mode and dose, for the prevention and management of cardiovascular disease.

Local Passive Heat for the Treatment of Hypertension in Autonomic Failure

Background

Supine hypertension affects a majority of patients with autonomic failure; it is associated with end‐organ damage and can worsen daytime orthostatic hypotension by inducing pressure diuresis and volume loss during the night. Because sympathetic activation prevents blood pressure (BP) from falling in healthy subjects exposed to heat, we hypothesized that passive heat had a BP‐lowering effect in patients with autonomic failure and could be used to treat their supine hypertension.

Methods and Results

In Protocol 1 (n=22), the acute effects of local heat (40–42°C applied with a heating pad placed over the abdomen for 2 hours) versus sham control were assessed in a randomized crossover fashion. Heat acutely decreased systolic BP by −19±4 mm Hg (versus 3±4 with sham, P<0.001) owing to decreases in stroke volume (−18±5% versus −4±4%, P=0.013 ) and cardiac output (−15±5% versus −2±4%, P=0.013). In Protocol 2 (proof‐of‐concept overnight study; n=12), we compared the effects of local heat (38°C applied with a water‐perfused heating pad placed under the torso from 10 pm to 6 am) versus placebo pill. Heat decreased nighttime systolic BP (maximal change −28±6 versus −2±6 mm Hg, P<0.001). BP returned to baseline by 8 am. The nocturnal systolic BP decrease correlated with a decrease in urinary volume (r=0.57, P=0.072) and an improvement in the morning upright systolic BP (r=−0.76, P=0.007).

Conclusions

Local heat therapy effectively lowered overnight BP in patients with autonomic failure and supine hypertension and offers a novel approach to treat this condition. Future studies are needed to assess the long‐term safety and efficacy in improving nighttime fluid loss and daytime orthostatic hypotension.

Registration

URL: https://www.clinicaltrials.gov; Unique identifiers: NCT02417415 and NCT03042988.

Impaired Endothelial Function in Patients With Postural Tachycardia Syndrome

The purpose of this study is to evaluate endothelial function in postural tachycardia syndrome (PoTS), a poorly understood chronic condition characterized by a state of consistent orthostatic tachycardia (delta heart rate ≥30 beats per minute) upon standing without orthostatic hypotension. Nineteen patients with PoTS and 9 healthy controls were studied after 3 days of a fixed, caffeine-free, normal sodium (150 milliequivalents/day) diet. All participants underwent autonomic function testing, including sinus arrhythmia, valsalva maneuver, hyperventilation, cold pressor, handgrip, and a standing test with catecholamine measurements, followed by endothelial function testing. We analyzed 3 measures of endothelial function: percent brachial flow-mediated dilation, digital pulsatile arterial tonometry, and postischemic percent leg blood flow. Flow-mediated dilation was significantly lower in patients with PoTS (6.23±3.54% for PoTS) than in healthy controls (10.6±4.37% for controls versus, P=0.014). PoTS and controls had similar digital pulsatile arterial tonometry (1.93±0.40 arbitrary units for controls versus 2.13±0.63 arbitrary units for PoTS). PoTS had similar but suggestive percent leg blood flow to controls (313±158% for PoTS versus 468±236% for controls, P=0.098). Patients with PoTS have significantly reduced flow-mediated dilation compared with healthy controls, suggesting that PoTS is characterized by endothelial dysfunction in conduit arteries. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01308099.

Splanchnic Venous Compression Enhances the Effects of ß-Blockade in the Treatment of Postural Tachycardia Syndrome

Background

Splanchnic venous pooling induced by upright posture triggers a compensatory increase in heart rate (HR), a response that is exaggerated in patients with postural tachycardia syndrome. To assess whether abdominal compression attenuates orthostatic tachycardia and improves symptoms, 18 postural tachycardia syndrome patients (32±2 years) were randomized to receive either abdominal compression (40 mm Hg applied with an inflatable binder ≈2 minutes before standing) or propranolol (20 mg) in a placebo‐controlled, crossover study.

Methods and Results

Systolic blood pressure, HR, and symptoms were assessed while seated and standing, before and 2 hours postdrug. As expected, propranolol decreased standing HR compared with placebo (81±2 versus 98±4 beats per minute; P<0.001) and was associated with lower standing systolic blood pressure (93±2 versus 100±2 mm Hg for placebo; P=0.002). Compression had no effect on standing HR (96±4 beats per minute) but increased standing systolic blood pressure compared with placebo and propranolol (106±2 mm Hg; P<0.01). Neither propranolol nor compression improved symptoms compared with placebo. In 16 patients we compared the combination of abdominal compression and propranolol with propranolol alone. The combination had no additional effect on standing HR (81±2 beats per minute for both interventions) but prevented the decrease in standing systolic blood pressure produced by propranolol (98±2 versus 93±2 mm Hg for propranolol; P=0.029), and significantly improved total symptom burden (−6±2 versus −1±2 for propranolol; P=0.041).

Conclusions

Splanchnic venous compression alone did not improve HR or symptoms but prevented the blood pressure decrease produced by propranolol. The combination was more effective in improving symptoms than either alone. Splanchnic venous compression can be a useful adjuvant therapy to propranolol in postural tachycardia syndrome.

Registration

URL: https://www.clini​caltr​ials.gov; Unique identifier: NCT00262470.

Novel malaria antigen Plasmodium yoelii E140 induces antibody-mediated sterile protection in mice against malaria challenge

Only a small fraction of the antigens expressed by malaria parasites have been evaluated as vaccine candidates. A successful malaria subunit vaccine will likely require multiple antigenic targets to achieve broad protection with high protective efficacy. Here we describe protective efficacy of a novel antigen, Plasmodium yoelii (Py) E140 (PyE140), evaluated against P. yoelii challenge of mice. Vaccines targeting PyE140 reproducibly induced up to 100% sterile protection in both inbred and outbred murine challenge models. Although PyE140 immunization induced high frequency and multifunctional CD8⁺ T cell responses, as well as CD4⁺ T cell responses, protection was mediated by PyE140 antibodies acting against blood stage parasites. Protection in mice was long-lasting with up to 100% sterile protection at twelve weeks post-immunization and durable high titer anti-PyE140 antibodies. The E140 antigen is expressed in all Plasmodium species, is highly conserved in both P. falciparum lab-adapted strains and endemic circulating parasites, and is thus a promising lead vaccine candidate for future evaluation against human malaria parasite species.

The use of ion-selective membranes to study cation transport in hybrid organic-inorganic perovskites

Using a methylammonium selective membrane in conjunction with electrochemical impedance spectroscopy, we measured ion migration in methylammonium lead triiodide (MAPbI₃) with a millisecond (ms) time constant under illumination. These values were consistent with the reported values of ionic conduction in thin-film perovskite solar cells. We monitored an electrochemical impedance response arising from ionic conductivity through MAPbI₃ and a methylammonium selective layer. We could fit this complex impedance response to an intuitive circuit model, which revealed an ionic species moving on a ms time scale. Electrospray ionization mass spectrometry (ESI-MS) revealed direct chemical evidence of methylammonium diffusion into the ion-selective layer. We found no experimental evidence indicating the mobility of lead ions or protons, suggesting that the mobile species observed under illumination is likely methylammonium.

Abstract 043: Local Passive Heat in the Treatment of Nocturnal Supine Hypertension in Autonomic Failure

Supine hypertension affects about half of patients with primary autonomic failure (AF), complicates the treatment of orthostatic hypotension (OH) and induces nocturnal polyuria, resulting in worsening of morning OH. We previously showed that short exposure to local passive heat (40-42°C applied for ≤2 hours over abdomen and pelvis with a heating pad) acutely decreased systolic blood pressure (BP) by -25±5 mmHg in AF patients with supine hypertension due to decreases in stroke volume (-29±5%) and cardiac output (-30±5%). In this study, we hypothesized that local passive heat therapy applied overnight would lower nocturnal BP and polyuria, and improve early morning OH in these patients. Ten AF patients with supine hypertension (age 76±2 years, 6 men, supine systolic BP 168±3 mmHg) received passive heat (38°C with a water-perfused heating pad placed under the torso) or placebo, in a 2-night crossover study. Supine BP was monitored every 2 hr from 8pm-8am. Heat therapy was applied from 10pm-6am. Morning orthostatic tolerance was assessed at 8 am. Systolic BP significantly decreased during overnight heat therapy compared to placebo (Figure; P<0.01 by mixed-effects model) with a maximal reduction of 30±6 mmHg at 4 hours of heat. Despite lowering nighttime BP, heat therapy did not decrease nocturnal diuresis or improve morning OH. In conclusion, low levels of local heat therapy applied overnight effectively lowers BP in AF patients with nocturnal supine hypertension. Thus, local heat therapy offers a novel non-pharmacologic approach to treat this condition, but future studies are needed to assess the long-term safety of this approach.

Abstract P1122: Sympathetic Vasodilation Improves Insulin-Mediated Microvascular Recruitment in the Forearm of Obese Subjects

Background: Obesity is associated with sympathetic activation which results in insulin resistance and a blunted insulin-mediated microvascular recruitment. We propose that removal of sympathetic vasoconstriction can result in improvement of insulin-mediated vasodilation and subsequently in sensitivity to insulin-mediated glucose uptake.

Methods: We blocked sympathetic vasoconstriction in an isolated forearm model during a hyperinsulinemic euglycemic clamp to determine the effect of insulin recruitment on microvascular circulation using contrast-enhanced ultrasonography (CEU). We studied 9 obese human subjects (age 41±6 years, BMI 37±3 kg*m -2 , SBP 125±6 mm Hg). We assessed the effects of insulin on microvascular recruitment and glucose uptake on two separate occasions, randomly assigned and at least one month apart, during an intrabrachial infusion of the alpha-adrenergic blocker phentolamine (PHE, 25 micrograms/min, blocked day) or saline (SAL, Control day). Subjects were studied at baseline (BSL) and at the end of the clamp (CLAMP).

Results: As expected forearm blood flow increased after insulin alone (67±27%, p=0.016) and with alpha blockade and insulin (140± 22%, p=0.0011). Microvascular blood volume (MBV, index of microvascular recruitment), showed a significant increased during PHE compared to SAL (figure). Muscle glucose uptake trended towards increase with PHE but did not reach statistical significance (p=0.0558). There were no systemic effects due to sympathetic blockade.

Conclusions: This data shows that sympathetic vasoconstriction contributes to the blunted insulin-mediated microvascular recruitment seen in obesity.

Correction: The use of ion-selective membranes to study cation transport in hybrid organic–inorganic perovskites

Correction for ‘The use of ion-selective membranes to study cation transport in hybrid organic–inorganic perovskites’ by Emily C. Smith et al., Phys. Chem. Chem. Phys., 2019, 21, 20720–20726.

Profiling the Targets of Protective CD8+ T Cell Responses to Infection

T cells are critical effectors of host immunity that target intracellular pathogens, such as the causative agents of HIV, tuberculosis, and malaria. The development of vaccines that induce effective cell-mediated immunity against such pathogens has proved challenging; for tuberculosis and malaria, many of the antigens targeted by protective T cells are not known. Here, we report a novel approach for screening large numbers of antigens as potential targets of T cells. Malaria provides an excellent model to test this antigen discovery platform because T cells are critical mediators of protection following immunization with live sporozoite vaccines and the specific antigen targets are unknown. We generated an adenovirus array by cloning 312 highly expressed pre-erythrocytic Plasmodium yoelii antigens into adenovirus vectors using high-throughput methodologies. The array was screened to identify antigen-specific CD8⁺ T cells induced by a live sporozoite vaccine regimen known to provide high levels of sterile protection mediated by CD8⁺ T cells. We identified 69 antigens that were targeted by CD8⁺ T cells induced by this vaccine regimen. The antigen that recalled the highest frequency of CD8⁺ T cells, PY02605, induced protective responses in mice, demonstrating proof of principle for this approach in identifying antigens for vaccine development.

Prevalence and Severity of Ratoon Stunt in Commercial Brazilian Sugarcane Fields

Brazil has 9 million ha of sugarcane, 85% of which are located in the Center-South area of the country. Field trials and surveys around the globe have shown that ratoon stunt disease (RSD), caused by Leifsonia xyli subsp. xyli, can severely reduce tonnage yield. Previous small-scale studies in Brazil have demonstrated RSD infection in all varieties, with values varying from 25 to 68%. Nevertheless, the prevalence and severity of RSD in commercial fields had not previously been assessed. To address this issue, we surveyed 13,173 ha in 1,154 fields of the eight main sugarcane varieties of the Center-South area, taking 92,114 samples from 50 mills in five different states. Our data showed that 10% of fields were infected, and that 58% of mills had at least one RSD-infected field. The variety RB92579 had the highest proportion of infected fields (17%) and, on average, the prevalence and severity in these fields was high compared with other varieties. RB867515, the most cultivated in Brazil, showed infection in 6.2% of sampled fields (5.5% of sampled area) causing an estimated annual economic loss of over US$1 million. This was the first time the economic importance of RSD on Brazilian commercial sugarcane production was estimated. The Cerrado region had the highest prevalence of RSD: 16% of fields, 17% of the cultivated area, and 82% of mills. The use of diseased planting material was identified in 9% of plant cane fields, representing 10% of the cultivated area. Copyright © 2017 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Does Personal Morality Exacerbate or Restrain Retaliation after Being Harmed?

To examine the effect of level of moral responsibility on response to being harmed, 80 undergraduates each were initially given 10 raffle tickets. Half of the participants subsequently had 9 of their 10 tickets taken away and given to a fellow participant, whereas half did not. In each of these harm-done conditions, half of the participants were led to believe that the fellow participant intentionally took 9 of their tickets (either successfully or not), whereas half believed that the fellow participant did not intend them harm. Participants were then given a chance to take tickets from the fellow. Responses revealed two independent processes, one to reestablish distributive justice after tickets had been taken and the other to retaliate for harm intended. Level of moral responsibility had no effect on pursuit of distributive justice, but high moral responsibility restrained pursuit of retributive (retaliatory) justice. Possible reasons are proposed.

Rosiglitazone modulates pigeon atherosclerotic lipid accumulation and gene expression in vitro

Atherosclerosis is a major contributor to the overall United States mortality rate, primarily in the form of heart attacks and stroke. Unlike the human disease, which is believed to be multifactorial, pigeon atherosclerosis is due to a single gene autosomal recessive trait. The White Carneau (WC-As) strain develops atherosclerotic plaques without the presence of known environmental risk factors such as diet and classic predictors such as blood pressure or blood cholesterol levels. With similar parameters, the Show Racer (SR-Ar) is resistant to plaque development. Thiazolidinediones, including rosiglitazone, activate the peroxisome proliferator-activated receptor gamma (PPARγ) raising cellular sensitivity to insulin. The effect of rosiglitazone was evaluated in aortic smooth muscle cells (SMC) from these 2 pigeon breeds. Primary SMC cultures were prepared from WC-As and SR-Ar squabs. Cell monolayers, which achieved confluence in 7 d, were treated with 0 or 4 µM rosiglitazone for 24 h. Cellular lipid accumulation was evaluated by oil red O staining. Control WC-As cells had significantly higher vacuole scores and lipid content than did the SR-Ar control cells. Rosiglitazone treatment decreased WC-As lipid vacuoles significantly compared with the control cells. On the other hand, lipid vacuoles in the treated and untreated SR-Ar cells did not differ significantly. The effect of rosiglitazone on WC-As SMC gene expression was compared with control SMC using representational difference analysis. Significant transcript increases were found for caveolin and RNA binding motif in the control cells compared with the rosiglitazone-treated cells as well as cytochrome p450 family 17 subfamily A polypeptide 1 (CYP171A) in the rosiglitazone-treated cells compared with the control cells. Although rosiglitazone was selected for these experiments because of its role as a PPARγ agonist, it appears that the drug also tempers c-myc expression, as genes related to this second transcription factor were differentially expressed. Both PPARγ and c-myc appear to affect WC-As SMC gene expression, which may relate to disease development, progression, or both.

Atherosclerosis-susceptible and atherosclerosis-resistant pigeon aortic cells express different genes in vivo

Spontaneous atherosclerosis in the White Carneau (WC-As) pigeon is inherited as a single gene disorder, and its progression closely mirrors the human disease. Representational difference analysis and microarray were used to identify genes that were differentially expressed between the susceptible WC-As and resistant Show Racer (SR-Ar) aortic tissue. The RNA extracted from 1-d-old squab aortas was used to make cDNA for each experiment. Fifty-six unique genes were found using representational difference analysis, with 25 exclusively expressed in the WC-As, 15 exclusive to the SR-Ar, and 16 nonexclusive genes having copy number variation between breeds. Caveolin and β-actin were expressed in the WC-As, whereas the proteasome maturation protein and the transcription complex CCR4-NOT were exclusive to the SR-Ar. Microarray analysis revealed 48 genes with differential expression. Vascular endothelial growth factor and p53 binding protein were among the 17 genes upregulated in the WC-As. Thirty-one genes were upregulated in the SR-Ar including the transforming growth factor-β signaling factor SMAD2 and heat shock protein 90. Genes representing several biochemical pathways were distinctly different between breeds. The most striking divergences were in cytoskeletal remodeling, proteasome activity, cellular respiration, and immune response. Actin cytoskeletal remodeling appears to be one of the first differences between susceptible and resistant breeds, lending support to the smooth muscle cell phenotypic reversion hypothesis of human atherogenesis.

Objectively measured patterns of physical activity in primary school children in Coventry: the influence of ethnicity

AIMS

The aetiology of increased metabolic risk in South Asians is incompletely understood, but may include modifiable factors such as physical activity. This study assessed patterns of physical activity in UK primary school children and examined the influence of ethnicity.

METHODS

We studied a community sample of children aged 8-9 years attending primary schools in Coventry, UK. One hundred and sixty-one children wore combined physical activity and heart rate monitors for 7 days. Levels of activity and energy expenditure were compared between White European (n = 96) and South Asian children (n = 65). Patterns of physical activity during the school week were also described.

RESULTS

Seventy-three per cent of White Europeans compared with only 35% of South Asians achieved international recommendations of 60 minutes of moderate to vigorous physical activity daily (P < 0.0000). South Asians were less active during the week (106 ± 28 vs. 120 ± 32 counts/min, respectively, P = 0.0054) and at weekends (92 ± 34 vs. 108 ± 54 counts/min, P = 0.0118) compared with White Europeans. There were differences in energy expenditure with lower physical activity levels in South Asians (daily average 1.68 ± 0.13 vs. 1.76 ± 0.17, P < 0.0001). Differences were attributable to less activity after school in South Asians (97 ± 29 vs. 120 ± 43 counts/min, P < 0.0000) as daytime activity was comparable between groups (120 ± 41 vs. 124 ± 39 counts/min, P > 0.05).

CONCLUSION

South Asian children in Coventry do significantly less physical activity than White Europeans, mainly attributable to differences in after-school activity. Ethnically tailored interventions should explore whether physical activity can be increased in South Asian children and, if so, whether this increased physical activity improves metabolic health.

Therapeutic vaccination expands and improves the function of the HIV-specific memory T-cell repertoire

BACKGROUND

The licensing of herpes zoster vaccine has demonstrated that therapeutic vaccination can help control chronic viral infection. Unfortunately, human trials of immunodeficiency virus (HIV) vaccine have shown only marginal efficacy.

METHODS

In this double-blind study, 17 HIV-infected individuals with viral loads of <50 copies/mL and CD4(+) T-cell counts of >350 cells/µL were randomly assigned to the vaccine or placebo arm. Vaccine recipients received 3 intramuscular injections of HIV DNA (4 mg) coding for clade B Gag, Pol, and Nef and clade A, B, and C Env, followed by a replication-deficient adenovirus type 5 boost (10(10) particle units) encoding all DNA vaccine antigens except Nef. Humoral, total T-cell, and CD8(+) cytotoxic T-lymphocyte (CTL) responses were studied before and after vaccination. Single-copy viral loads and frequencies of latently infected CD4(+) T cells were determined.

RESULTS

Vaccination was safe and well tolerated. Significantly stronger HIV-specific T-cell responses against Gag, Pol, and Env, with increased polyfunctionality and a broadened epitope-specific CTL repertoire, were observed after vaccination. No changes in single-copy viral load or the frequency of latent infection were observed.

CONCLUSIONS

Vaccination of individuals with existing HIV-specific immunity improved the magnitude, breadth, and polyfunctionality of HIV-specific memory T-cell responses but did not impact markers of viral control.

CLINICAL TRIALS REGISTRATION

NCT00270465.

Investigation of contact acoustic nonlinearities on metal and composite airframe structures via intensity based health monitoring

Nonlinear structural intensity (NSI) and nonlinear structural surface intensity (NSSI) based damage detection techniques were improved and extended to metal and composite airframe structures. In this study, the measurement of NSI maps at sub-harmonic frequencies was completed to provide enhanced understanding of the energy flow characteristics associated with the damage induced contact acoustic nonlinearity mechanism. Important results include NSI source localization visualization at ultra-subharmonic (nf/2) frequencies, and damage detection results utilizing structural surface intensity in the nonlinear domain. A detection metric relying on modulated wave spectroscopy was developed and implemented using the NSSI feature. The data fusion of the intensity formulation provided a distinct advantage, as both the single interrogation frequency NSSI and its modulated wave extension (NSSI-MW) exhibited considerably higher sensitivities to damage than using single-sensor (strain or acceleration) nonlinear detection metrics. The active intensity based techniques were also extended to composite materials, and results show both NSSI and NSSI-MW can be used to detect damage in the bond line of an integrally stiffened composite plate structure with high sensitivity. Initial damage detection measurements made on an OH-58 tailboom (Penn State Applied Research Laboratory, State College, PA) indicate the techniques can be transitioned to complex airframe structures achieving high detection sensitivities with minimal sensors and actuators.

CD4 T follicular helper cell dynamics during SIV infection

CD4 T follicular helper (TFH) cells interact with and stimulate the generation of antigen-specific B cells. TFH cell interaction with B cells correlates with production of SIV-specific immunoglobulins. However, the fate of TFH cells and their participation in SIV-induced antibody production is not well understood. We investigated the phenotype, function, location, and molecular signature of TFH cells in rhesus macaques. Similar to their human counterparts, TFH cells in rhesus macaques represented a heterogeneous population with respect to cytokine function. In a highly differentiated subpopulation of TFH cells, characterized by CD150lo expression, production of Th1 cytokines was compromised while IL-4 production was augmented, and cells exhibited decreased survival, cycling, and trafficking capacity. TFH cells exhibited a distinct gene profile that was markedly altered by SIV infection. TFH cells were infected by SIV; yet, in some animals, these cells actually accumulated during chronic SIV infection. Generalized immune activation and increased IL-6 production helped drive TFH differentiation during SIV infection. Accumulation of TFH cells was associated with increased frequency of activated germinal center B cells and SIV-specific antibodies. Therefore, chronic SIV does not disturb the ability of TFH cells to help B cell maturation and production of SIV-specific immunoglobulins.

Differentially expressed genes in aortic smooth muscle cells from atherosclerosis-susceptible and atherosclerosis-resistant pigeons

Susceptibility to spontaneous atherosclerosis in the White Carneau (WC-As) pigeon shows autosomal recessive inheritance. Aortic smooth muscle cells (SMC) cultured from susceptible WC-As and resistant Show Racer (SR-Ar) pigeons exhibit developmental and degenerative features corresponding to the respective SMC at atherosclerosis-prone sites in vivo. We used representational difference analysis to identify differentially expressed genes between WC-As and SR-Ar aortic SMC. Total RNA was extracted from cultured primary SMC of each breed, converted to double-stranded cDNA, followed by direct comparison in reciprocal representational difference analysis experiments. Difference products were cloned, sequenced, and identified by BLAST against the chicken genome. Six putative biochemical pathways were distinctly different between breeds with genes involved in energy metabolism and contractility exhibiting the most striking disparity. Genes associated with glycolysis and a synthetic SMC phenotype were expressed in WC-As cells. In contrast, SR-Ar cells expressed genes indicative of oxidative phosphorylation and a contractile SMC phenotype. In WC-As cells, the alternatives of insufficient ATP production limiting contractile function or the lack of functional contractile elements downregulating ATP synthesis cannot be distinguished due to the compressed in vitro versus in vivo developmental time frame. However, the genetic potential for effectively coupling energy production to muscle contraction present in the resistant SR-Ar was lacking in the susceptible WC-As.

Myasthenic syndrome caused by plectinopathy

BACKGROUND

Plectin crosslinks intermediate filaments to their targets in different tissues. Defects in plectin cause epidermolysis bullosa simplex (EBS), muscular dystrophy (MD), and sometimes pyloric atresia. Association of EBS with a myasthenic syndrome (MyS) was documented in a single patient in 1999.

OBJECTIVES

To analyze the clinical, structural, and genetic aspects of a second and fatal case of EBS associated with a MyS and search for the genetic basis of the disease in a previously reported patient with EBS-MD-MyS.

METHODS

Clinical observations; histochemical, immunocytochemical, and electron microscopy studies of skeletal muscle and neuromuscular junction; and mutation analysis.

RESULTS

An African American man had EBS since early infancy, and progressive muscle weakness, hyperCKemia, and myasthenic symptoms refractory to therapy since age 3 years. Eventually he became motionless and died at age 42 years. At age 15 years, he had a marked EMG decrement, and a reduced miniature endplate potential amplitude. The myopathy was associated with dislocated muscle fiber organelles, structurally abnormal nuclei, focal plasmalemmal defects, and focal calcium ingress into muscle fibers. The neuromuscular junctions showed destruction of the junctional folds, and remodeling. Mutation analysis demonstrated a known p.Arg2319X and a novel c.12043dupG mutation in PLEC1. The EBS-MD-MyS patient reported in 1999 also carried c.12043dupG and a novel p.Gln2057X mutation. The novel mutations were absent in 200 Caucasian and 100 African American subjects.

CONCLUSIONS

The MyS in plectinopathy is attributed to destruction of the junctional folds and the myopathy to defective anchoring of muscle fiber organelles and defects in sarcolemmal integrity.

Trichothiodystrophy with dysmyelination and central osteosclerosis

Trichothiodystrophy (TTD) is a rare group of autosomal recessive disorders of DNA repair unified by the presence of sulfur-deficient brittle hair. We report a 3-year-old boy with classic clinical features of TTD, including ichthyosis, alopecia, developmental delay, and tiger-tail banding of the hair shaft on polarizing microscopy. Brain MR imaging showed both diffuse dysmyelination and osteosclerosis, findings that, in combination, may be specific for TTD.

Ruptured maxillary retention cyst: cause of unilateral rhinorrhea after trauma

This study describes a case of a patient with traumatic rupture of a maxillary sinus retention cyst, which had an interesting clinical presentation of unilateral rhinorrhea, mimicking a CSF leak. The diagnosis was made fortuitously by comparison of a posttraumatic CT brain examination with a CT sinus study performed 1 day earlier.

Cardiac ECMO for biventricular hearts after paediatric open heart surgery

OBJECTIVE

To delineate predictors of hospital survival in a large series of children with biventricular physiology supported with extracorporeal membrane oxygenation (ECMO) after open heart surgery.

RESULTS

81 children were placed on ECMO after open heart surgery. 58% (47 of 81) were transferred directly from cardiopulmonary bypass to ECMO. Hospital survival was 49% (40 of 81) but there were seven late deaths among these survivors (18%). Factors that improved the odds of survival were initiation of ECMO in theatre (64% survival (30 of 47)) rather than the cardiac intensive care unit (29% survival (10 of 34)) and initiation of ECMO for reactive pulmonary hypertension. Important adverse factors for hospital survival were serious mechanical ECMO circuit problems, renal support, residual lesions, and duration of ECMO.

CONCLUSIONS

Hospital survival of children with biventricular physiology who require cardiac ECMO is similar to that found in series that include univentricular hearts, suggesting that successful cardiac ECMO is critically dependent on the identification of hearts with reversible ventricular dysfunction. In our experience of postoperative cardiac ECMO, the higher survival of patients cannulated in the operating room than in the cardiac intensive care unit is due to early effective support preventing prolonged hypoperfusion and the avoidance of a catastrophic cardiac arrest.

Susceptibility to spontaneous atherosclerosis in pigeons: an autosomal recessive trait

The inheritance pattern for susceptibility to spontaneous (noninduced) aortic atherosclerosis in pigeons was determined by crossbreeding and backcrossing experiments with atherosclerosis-susceptible White Carneau and atherosclerosis-resistant Show Racer breeds. Susceptibility, assessed by the presence of grossly visible lesions at the celiac bifurcation of the aorta at 3 years of age, demonstrated an inheritance pattern consistent with an autosomal recessive Mendelian trait. Cell culture studies indicated that susceptibility is a constitutive property of aortic cells as evidenced by vacuole formation and lipid content in smooth muscle cells from various tissues in susceptible pigeons.

Peripheral versus central muscarinic effects on blood pressure, cardiac contractility, heart rate, and body temperature in the rat monitored by radiotelemetry

Our laboratory has found that the organophosphate pesticide chlorpyrifos elicits an elevation in blood pressure that persists for approximately 24 hr after exposure. Since organophosphate pesticides inhibit acetylcholinesterase activity and cause cholinergic stimulation in the central nervous system and peripheral tissues, we suspect that the hypertensive response from chlorpyrifos is elicited by activation of pressor areas in the brain stem, specifically muscarinic receptors which are known to mediate hypertensive responses. Oxotremorine, a muscarinic agonist, should elicit a blood pressure response similar to organophosphate pesticides. This study used radiotelemetry to assess the effects of oxotremorine on blood pressure, heart rate, core temperature, QA interval (a measure of cardiac contractility), and motor activity in the male, Long-Evans rat. Subcutaneous co-administration of 0.2 mg/kg oxotremorine with 1.0 mg/kg methyl scopolamine (i.e., to block oxotremorine's peripheral effects) caused a marked elevation in blood pressure that developed concomitantly with a 2 degrees decrease in core temperature, 60 beats/min. increase in heart rate, increase in cardiac contractility but no change in motor activity. Overall, blood pressure increased by 19 mmHg from baseline and the response persisted for approximately 12 hr after injection. Methyl scopolamine alone increased heart rate but had no effect on blood pressure, core temperature, and motor activity. Oxotremorine injected without methyl scopolamine led to a relatively minor increase in blood pressure and hypothermia. Overall, central muscarinic stimulation with oxotremorine and methyl scopolamine leads to a vigorous hypertensive response that is associated with increased cardiac contractility, suggesting an increase in cardiac output. Combined central and peripheral cholinergic stimulation following oxotremorine without methyl scopolamine, as would also occur with exposure to chlorpyrifos and other organophosphate pesticides, did not elicit as much of a hypertensive response. This would suggest pathways other than those controlled directly with muscarinic receptors are operative in the development of chlorpyrifos-induced hypertension.

A role for cytokines in potentiation of malaria vaccines through immunological modulation of blood stage infection

Malaria is the world's major parasitic disease, for which effective control measures are urgently needed. One of the difficulties hindering successful vaccine design against Plasmodium is an incomplete knowledge of antigens eliciting protective immunity, the precise types of immune response for which to aim, and how these can be induced. A greater appreciation of the mechanisms of protective immunity, on the one hand, and of immunopathology, on the other, should provide critical clues to how manipulation of the immune system may best be achieved. We are studying the regulation of the balance between T helper 1 (Th1) and T helper 2 (Th2) CD4+ T lymphocytes in immunity to asexual blood stages of malaria responsible for the pathogenicity of the disease. Protective immunity to the experimental murine malarias Plasmodium chabaudi and Plasmodium yoelii involves both Th1 and Th2 cells, which provide protection by different mechanisms at different times of infection characterised by higher and lower parasite densities, respectively. This model therefore facilitates a clearer understanding of the Th1/Th2 equilibrium that appears central to immunoregulation of all host/pathogen relationships. It also permits a detailed dissection in vivo of the mechanisms of antimalarial immunity. Here, we discuss the present state of malaria vaccine development and our current research to understand the factors involved in the modulation of vaccine-potentiated immunity.

A dichotomous role for nitric oxide in protection against blood stage malaria infection

Nitric oxide (NO) is cytotoxic and cytostatic to blood stage malaria parasites in vitro, but the precise mechanism(s) by which it mediates an effect in vivo is not known. In particular, whether or not control of acute parasitemia depends on the presence of NO is unclear. We have shown previously that blocking NO synthesis at the time of its induction may cause an increase in peak primary parasitemia during infection of mice with Plasmodium chabaudi, suggesting that NO may be parasiticidal in vivo. However, as recent data indicate that NO suppresses Th1 cell proliferation in vitro by downregulating IL-2 production, we have investigated whether this immunoregulatory function of NO affects its capacity for anti-malarial activity. Treatment of P. chabaudi-infected mice with the iNOS inhibitor aminoguanidine hemisulfate (AG) starting just prior to the peak of primary parasitemia caused a significant elevation and extension of the acute infection and led to a partial but significant abrogation of the suppression of spleen cell proliferation to both mitogen and specific antigen observed when NO synthesis was not blocked. In the absence of NO, levels of IL-2, but not of IFN-gamma, TNF-alpha, or of any Th2-regulated cytokines examined, increased significantly. However, when AG treatment was brought forward to the early ascending phase of primary parasitemia, significantly increased levels of IFN-gamma and TNF-alpha, as well as of IL-2, were observed over those for infected control mice similarly treated with phosphate-buffered saline. Moreover, despite the absence of NO, parasitemias of AG-treated mice were not significantly elevated. The effect of AG therefore appeared to be dependent upon the timing of its administration in vivo. We propose that during malaria infections, there is a dynamic balance between the regulatory and anti-parasitic roles of NO. While the immunosuppressive function of NO leads to a downregulation in vivo of production of IL-2, and indirectly of IFN-gamma and TNF-alpha, this perceived weakening of the host cell-mediated immune response is in part masked by the protective anti-malarial effects of NO itself.

Modulation of experimental blood stage malaria through blockade of the B7/CD28 T-cell costimulatory pathway

Recent studies have implicated cytokines associated with CD4+ T lymphocytes of both T helper (Th)1 and Th2 subsets in resistance to experimental blood stage malaria. As the B7/CD28 costimulatory pathway has been shown to influence the differentiation of Th cell subsets, we investigated the contribution of the B7 molecules CD80 and CD86 to Th1/Th2 cytokine and immunoglobulin isotype profiles and to the development of a protective immune response to malaria in NIH mice infected with Plasmodium chabaudi. Effective blockade of CD86/CD28 interaction was demonstrated by elimination of interleukin (IL)-4 and up-regulation of interferon (IFN)-gamma responses by P. chabaudi-specific T cells and by reduction of P. chabaudi-specific immunoglobulin G1 (IgG1). The shift towards a Th1 cytokine pattern corresponded with efficient control of acute parasitaemia but an inability to resolve chronic infection. Moreover, combined CD80/CD86 blockade by using anti-CD80 and anti-CD86 monoclonal antibodies raised IFN-gamma production over that seen with CD86 blockade alone, with augmentation of this Th1-associated cytokine reducing levels of peak primary parasitaemia. These results demonstrate that IL-4 production by T cells in P. chabaudi-infected NIH mice is dependent upon CD86/CD28 interaction and that IL-4 and IFN-gamma contribute significantly, at different times of infection, to host resistance to blood stage malaria. In addition, combined CD80/CD86 blockade resulted in preferential expansion of IFN-gamma-producing T cells during P. chabaudi infection, suggesting that costimulatory pathways other than B7/CD28 may contribute to T-cell activation during continuous antigen stimulation. This study indicates a role for B7/CD28 costimulation in modulating the CD4+ T-cell response during malaria, and further suggests involvement of this pathway in other infectious and autoimmune diseases in which the Th cell immune response is also skewed.